Unbalance on a rotary member such as a wheel can be measured by means of an apparatus having a rotary mounting arrangement for supporting the rotary member whose unbalance is to be measured, the rotary mounting arrangement being supported on a foundation structure of the apparatus by way of an oscillatable support assembly. A device for measuring forces and/or oscillations is disposed between the foundation structure and the rotary mounting arrangement and serves to measure centrifugal forces and/or oscillations which result from unbalance of the rotary member which is rotatably mounted by the rotary mounting arrangement. Such an apparatus which is disclosed in DE 37 16 210 C2, U.S. Pat. No. 4,905,515, can be in the form of a vertical machine which therefore has a vertical mounting for the spindle for carrying the rotary member, or a horizontal machine with a horizontal spindle mounting.
There are however situations in which, besides unbalance on the rotary member, the mass of the rotary member or run-out thereof is also to be measured. For example, when classifying motor vehicle tires, the unbalance is related to the outside radius and the unbalance mass is then related to the tire mass. The unbalance mass occurs as a given fraction of the tire mass, which can also be represented as a percentage value of the tire mass. Tire classification is then effected in accordance with specific limit values in respect of admissible percentage values of that kind.